|
Egr
Just thought I would chime in on this thread;
I have a Positive displacement Supercharged vehicle and disabled the EGR system after installing an AIR-WATER intercooler between the Supercharger and the intake manifold.
My reasoning was to keep the intercooler and valves cleaner.
I did this over 4 years ago, amung many other modifications.
I feel that this did result in a slight reduction in fuel economy however it may all be in my head as I can't quite explain why it would matter much when accounted for.
....
My understanding as to why:
1) Pumping loses. (minor)
Why? With the throttle at at whatever position, lets call it closed, x amount of air is metered and allowed into the intake manifold. this minor amount of air only slightly reduces the vacuum the pistons have to work against.
A functioning EGR would further reduce back-pressure, without introducing addtional oxygen effectively maintaining the air/fuel ratio and injector flow rates.
On the flip side, the reduction in vacuum also leads to increased 'windage' however minor.
2) Ignition spark / Timing Advance / Retard (moderate)
Without EGR the fresh air entering the combustion chamber when mixed with fuel will burn faster, because it is burning faster this could lead to knock / detonation. Assuming the timing is corrected for this condition (reduced) the mixture will ignite later and possibly result in more burn occuring after the power stroke and during the exhaust stroke effectively adding heat to the valves / ehaust / heads that would otherwise be.. wasted due to poor burn? (less power) but that would mean better fuel economy.
...
Will you see more power (WOT) with EGR disabled? I don't think so, because the EGR closes during WOT anyway.
...
|